Third generation partnership project (3GPP) mobile communication systems based on a wideband code division multiple access (WCDMA) radio access technology are widely spread all over the world. High-speed downlink packet access (HSDPA) that can be defined as a first evolutionary stage of WCDMA provides 3GPP with a radio access technique that is highly competitive in the mid-term future. However, since requirements and expectations of users and service providers are continuously increased and developments of competing radio access techniques are continuously in progress, new technical evolutions in 3GPP are required to secure competitiveness in the future.
Hereinafter, a downlink (DL) denotes a communication link from a base station (BS) to a user equipment (UE), and an uplink (UL) denotes a communication link from the UE to the BS.
The BS schedules radio resources allocated to the UE. A resource block is a basic unit of radio resources allocated to the UE. The BS allocates al least one resource block to the UE. DL data or UL data is transmitted using the resource block allocated to the UE. For frequency diversity, actual data can be transmitted in a distributed manner over the entire frequency band. This is called distributed transmission. A resource block allocated to the UE is referred to as a virtual resource block. A resource block in an actual physical channel is referred to as a physical resource block. For distributed data transmission, the physical resource block is divided into a plurality of sub-parts. The virtual resource block is mapped in a distributed manner to sub-parts each of which belongs to different physical resource blocks. The physical resource block includes reference signals for demodulation. The number of reference signals arranged for each sub-part may not be constant. As the number of reference signals increases, the region for data transmission is reduced. In a case where the virtual resource block is persistently mapped to specific sub-parts including more reference signals than other sub-parts, an actual region for data transmission is allocated less in size than other virtual resource blocks. As a result, an effective code rate for data transmission increases. When the effective code rate increases, transmitted data is significantly affected by a channel environment.
Accordingly, there is a need for a method for allocating an actual resource region having a constant size with respect to each of virtual resource blocks irrespective of arrangement of reference signals when data is transmitted in a distributed transmission procedure.